EXACTLY SOLUBLE MODEL OF A QUANTUM SYSTEM IN EXTERNAL-FIELD WITH PERIODIC TIME-DEPENDENCE

A model is proposed, in which all possible transitions occuring in a quantum system exposed for a finite time to an external field of the form V(t)=V cos (Ωt+δ) can be calculated exactly. The basic assumption making the model soluble is the separable form of the operator V. The dynamical equation is transformed from t (time) to ω (energy) variable and the resulting finite difference equation is solved for a c-number function f(ω), in terms of which all the transition amplitudes can be expressed. In the considered numerical example we studied the dependence of the spectrum of the emitted particles on the field strength and pulse length. © 1990 Springer-Verlag.